(1. China Three Gorges Corporation，Beijing 100038，China；2. Engineering Research Center of Rock-soil Drilling and Excavation and Protection，Ministry of Education，China University of Geosciences，Wuhan，Hubei 430074，China；3. Zhejiang HydroChina-ITASCA R and D Center，Hangzhou，Zhejiang 310014，China；4. HydroChina Huadong Engineering Corporation，Hangzhou，Zhejiang 310041，China)
Abstract：The proposed hydropower station which is located on lower reaches of Jinsha River is characterized by the large scale and complex arrangement. The height of cylindrical throttled surge chamber is about 100 m，and the diameter reaches 50 m. The stability and supporting measures of chamber arch are the noteworthy factors needed to be considered. In order to analyze potential stress-type failure，deformation and collapse caused by structure planes of tailrace surge chamber arch crowns under complex geological conditions，engineering geological analysis and three-dimensional numerical simulation(3DEC) are adopted to study the stress concentration arrange，stress concentration degree and risk of high stress failure，and the effects of interlayer fault zones on stability of surrounding rock are demonstrated. The results show that the overall stability of cavern satisfies the engineering requirements，and the relatively stress concentration degree(30–44 MPa) of arch crown doesn?t cause prominent issue of high stress failure. However，bedding fault zones reduce the stability of surrounding rock distinctly，thus large sliding deformation occurred along the bedding fault zones and shear yield occurred in NNE direction from surface to 7 m superficial zone. After strengthened reinforcements including system supporting and concrete replace are adopted，sliding deformation of bedding fault zones is reduce obviously，and interlaminar band security reserve is improved.
[1] 魏进兵，邓建辉，王俤剀，等. 锦屏一级水电站地下厂房围岩变形与破坏特征分析[J]. 岩石力学与工程学报，2010，29(6)：1 198–1 205. (WEI Jinbing，DENG Jianhui，WANG Dikai，et al. Characterization of deformation and fracture for rock mass in underground powerhouse of Jinping Hydropower Station[J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(6)：1 198– 1 205.(in Chinese))
[2] 江 权，冯夏庭，陈国庆，等. 高地应力条件下大型地下洞室群稳定性综合研究[J]. 岩石力学与工程学报，2008，27(增2)：3 769–3 777. (JIANG Quan，FENG Xiating，CHEN Guoqing，et al. Stability study of large underground caverns under high geostress[J]. Chinese Journal of Rock Mechanics and Engineering，2008，27(Supp.2)：3 769–3 777. (in Chinese))
[3] 石广斌，李 宁. 高地应力下大型地下硐室块体变形特征及其稳定性分析[J]. 岩石力学与工程学报，2009，28(增1)：2 884–2 890.(SHI Guangbin，LI Ning. Analyses of block deformation characteristics of large underground cavern and its stability under high in-situ stress[J]. Chinese Journal of Rock Mechanics and Engineering，2009，28(Supp.1)：2 884–2 890.(in Chinese))
[4] 黄 可，吕 慷，徐江涛，等. 金沙江白鹤滩水电站可行性研究报告(厂区地下洞室群围岩稳定专题研究报告)[R]. 杭州：中国水电工程顾问集团华东勘测设计研究院，2011.(HUANG Ke，LU Kang，XU Jiangtao，et al. Feasibility study report of Baihetan hydropower project located on Jinsha River(research report of surrounding rock stability of underground caverns)[R]. Hangzhou：HydroChina Huadong Engineering Corporation，2011.(in Chinese))
[5] 谢 晔，刘 军，李仲奎，等. 在大型地下开挖中围岩块体稳定性分析[J]. 岩石力学与工程学报，2006，25(2)：306–311.(XIE Ye，LIU Jun，LI Zhongkui，et al. Stability analysis of block in surrounding rock mass of large underground excavation[J]. Chinese Journal of Rock Mechanics and Engineering，2006，25(2)：306–311.(in Chinese))
[6] CUNDALL P A. A computer model for simulating progressive large scale movements in blocky rock systems[C]// Proceedings of the International Symposium on Rock Mechanics. Nancy，France：[s.n.]，1971：2–8.
2012, Vol. 31 
